Characteristics of microplastic release from self-heating food packaging and its health risks to human population

While existing research on microplastics (MPs) migration has predominantly focused on microwave-heated plastic containers and short-term exposure within liquid media, the exposure characteristics and human health risks associated with the emerging scenario of self-heating foods remain poorly understood. To address this research gap, this study pioneeringly established a MP migration simulation framework based on realistic self-heating dynamics. Integrating nationwide survey data from 916 consumers, we developed a novel behavior-based exposure risk assessment model. Crucially, we introduced an innovative consumption-weighted frequency parameter to explicitly capture real-world dietary patterns within the exposure modeling framework. By quantitatively evaluating the estimated daily intake (EDI) of MPs across both the general population and sensitive demographics, this work provides compelling empirical evidence and a robust methodological foundation for evaluating packaging-derived MP risks in self-heating foods. The results showed that high temperature, long contact time, and high-fat, acidic media significantly exacerbated the migration and release of MPs. Under 100 °C conditions, the MP concentration in the olive oil simulant was 5.7 times that under 40 °C conditions, while the acidic environment (3% acetic acid) led to a 2- to 5-fold increase in MP release compared to that under deionized water (DI). In the sensitive population, the EDI value of self-heating rice for children aged 0–7 was as high as 1221 ± 592 particles/(kg·d). Self-heating noodle soup exhibited the highest MP contamination risk, self-heating rice showed a moderately high risk. The MP exposure risk from self-heating foods warrants further attention, especially for sensitive groups such as children.